The haskell-type-exts package

Haskell Types with Extensions (HTE, haskell-type-exts)
is (an embryo of) a type checker for Haskell as embodied
syntactically by the haskell-src-exts (HSE) package.
At this point the type checker only handles a limited
number of extensions, both regarding the various syntactic
extensions handled by HSE, and the various type-level
extensions implemented in e.g. GHC. The goal is to
cover the full range of known Haskell extensions,
but every path starts with a first step.